how to test for leak in pump

i recently bought a new brake bleeding kit containing a brass metal hand pump. i have fitted my couplers and hoses etc.. all seem to fine. i can't get any suction though. i can place the coupler end on my skin and give a few pumps and receive and maintain a vaccum, but when i connect to the cylander, i loose vaccum. the female coupler is new and made of metal. is it possible the cylinder could be wrecked? is there any way of testing what exactly is defective before i purchase any more parts?

tried the couplers together w/o the cylinder and vaccum was good. guess i'll start shopping for a new cylinder.

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Before you rush out and speen money needlessly, are you sure it's trhe cylinder? You say you lose prssure, so I assume you pump up ok, but after a while the pressure falls off? First of all, check the connections to make sure they're air tight. Then makesure your pubs are trimmed around the base whrere the cylinder sits; it's surprising how much air can get in with just a few rogue hairs trapped inside. Also use a heavy lube/cream to help withthe seal